math help

What is 3/20 + 4/12?

What is 3/20 + 4/12?

Here's how we add

3
20
+
4
12

Step 1

Can you add yet? Nope! The denominators don't match. We need a common denominator. So next we take both denominators and multiply them. Next, take each numerator and multiply it by the denominator of the other term.

So, we multiply 3 by 12, and get 36, then we multiply 20 by 12 and get 240.

3/20 times 12

Now for the second term. You multiply 4 by 20, and get 80, then multiply 20 by 12 and get 240.

4/12 times 20

We now have a new problem, that looks like this:

36
240
+
80
240

Step 2

Since our denominators match, we can add the numerators.

36 + 80 = 116

That gives us the sum, which is

116
240

Step 3

Now, do we need to simplify this fraction?

First, we attempt to divide it by 2...

Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:

116
240
÷ 2 =
58
120

Let's try dividing by that again...

Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:

58
120
÷ 2 =
29
60

Let's try dividing by that again...

Nope! So now we try the next greatest prime number, 3...

Nope! So now we try the next greatest prime number, 5...

Nope! So now we try the next greatest prime number, 7...

Nope! So now we try the next greatest prime number, 11...

Nope! So now we try the next greatest prime number, 13...

Nope! So now we try the next greatest prime number, 17...

Nope! So now we try the next greatest prime number, 19...

Nope! So now we try the next greatest prime number, 23...

Nope! So now we try the next greatest prime number, 29...

Nope! So now we try the next greatest prime number, 31...

No good. 31 is larger than 29. So we're done reducing.

There you have it! Here's the final answer to 3/20 + 4/12

3
20
+
4
12
=
29
60
© 2014 Randy Tayler